Field of the Invention
The present invention relates to a vehicle wheel axle connector adapter, particularly including the ability to adapt the axle to a frame dropout with an open slot. The adapter may provide a threaded portion to receive the axle and/or to receive a portion of the axle. More specifically, the adapter is rotationally keyed to the dropout to limit rotation of the adapter relative to the dropout to aid in the installation of the adapter to the dropout and/or the assembly of the axle to the adapter.
Discussion of Prior Art
Heretofore, in the case where the axle is threadably connected to the dropout of a bicycle frame, the external threads of the axle are threadably connected to an internally threaded hole formed directly into the dropout. Since such a closed threaded hole circumferentially surrounds the axle, it is considered a “closed dropout”. In some cases, a closed dropout utilizes an internally threaded insert that is positioned within a “closed” hole of the dropout, which is also referred to as a “closed dropout”. This is in contrast to the open slot commonly associated with bicycle dropouts, which is commonly referred to as an “open dropout”, since the slot has an opening. Most open dropouts are designed to be used in conjunction with a quick-release skewer as a means to attach the axle to the bicycle frame.
With the advent of mountain bikes and disc brakes, and with the desire to have a more robust and stiff wheel attachment system, the through-axle has been utilized as a heavier-duty wheel attachment system to replace the quick-release skewer system. This through-axle commonly threads directly into the closed dropout of a frame or fork of the bicycle. There are also alternative wheel attachment designs, similar to that described in FIGS. 4a-f of U.S. Pat. No. 6,089,675 that utilize a closed dropout for threadable connection with the axle.
The problem is that most bicycles on the road today utilize an open dropout with an open slot. Thus, it is desirable to adapt the existing open dropout design to a closed dropout configuration that permits the threadable connection with an axle. One such adapter was utilized in the 1960's, when the short-lived Cinelli Bivalent hub system utilized an adapter that created an internally threaded hole in a conventional open slotted dropout. However, this Cinelli Bivalent adapter was difficult to use because the adapter was not rotationally locked or keyed to the dropout. As such, this adapter would have a tendency to twist and rotate as it was being assembled to the dropout by means of the clamp nut. Additionally, as the axle was threadably assembled and disassembled to the adapter, this twisting action would have a tendency to threadably loosen the threaded connection between the adapter and the clamp nut, thereby loosening the connection between the dropout and the adapter. This creates a grave safety concern, as a loose adapter may permit the wheel to become separated from the bicycle frame. Still further, since this adapter is not rotationally keyed to the dropout, the mechanic must exercise proper judgment and care to insure that the adapter is properly circumferentially aligned with the dropout. If the mechanic makes an error, then the geometry of the adapter may bot be properly aligned to receive the axle and the hub. All of these limitations and shortcomings, among others, of the Cinelli Bivalent adapter makes this system unsuitable for utilization with modern bicycles, particularly when disc brakes or other hub-mounted braking systems are utilized.